ID:15840 outclk port of Clock Control Block "<name>" with CLOCK_TYPE parameter set to EXTERNAL_CLOCK_OUTPUT drives <name>, but must drive an unregistered pin

CAUSE: The outclk port of the specified Clock Control Blocks drives the specified illegal source. When the CLOCK_TYPE parameter of the specified Clock Control Block is set to EXTERNAL_CLOCK_OUTPUT, the outclk port of the specified Clock Buffer Block must drive an unregistered pin.

ACTION: Modify the design so that the outclk port of the specified Clock Buffer Block drives an unregistered pin.